We've heard it a handful of times before, but here we are again: some OEM is announcing that it's experimenting with a dual-boot Windows / Android project, or in this case, a project that will allow users to switch their handset from an Android phone to a Windows phone with a simple tool. Microsoft has teamed up with Xiaomi to test this concept on the Mi 4, but mostly as a way to get market feedback on Windows 10 for smartphones in China.